Any production process is characterized by certain physical, chemical and biological parameters. During the process certain ones of the more important parameters should be maintained at a pre-set or corrected level. For that purpose, various automatic control systems are used which consist of three main parts: a meter, a regulator and an actuator. Stepless or relay-type actuators may be used.
Known in the art are apparatus for automatically stabilizing a process of thermal treatment of liquid media, comprising a sterilization chamber which is in contact with a heat-exchange jacket, a device for thermally controlling the process being conducted which is connected to a source of a coolant and communicates with the sterilization chamber and the heat-exchange jacket, such apparatus being described in U.S. Pat. No. 3,445,341 and publicity leaflet by New Brunswick Scientific Co. Inc., model FM-250, Technical Description and Operation Manual.
In such apparatus the device for thermally controlling the process being conducted comprises a temperature sensor which is installed in the sterilization chamber and a valve which is electrically coupled to the temperature sensor, installed in a pipeline connecting the source of a coolant to the heat-exhange jacket. Such apparatus ensures the feeding of a coolant to the sterilization chamber in response to a signal from the sensor.
The above-described apparatus operates in response to a signal from the temperature sensor installed in the sterilization chamber so that the process temperature over the whole volume being sterilized cannot be traced, and only a local zone in which the sensor is installed can be monitored. This monitoring of the sterilization temperature frequently results in incomplete sterilization or overheating of a studied sample. Thermolabile components of solutions, such as glucose, which are sterilized at relatively low temperature and caramelized at increased temperature are especially sensitive to the temperature conditions. In addition, such apparatus have a relay actuation of the valve controlling heat carrier or coolant flow so that as temperature fluctuations in the sterilization chamber occur, the exposure time of a sample changes, and the sample may be deteriorated.